1. Field of the Invention
The present invention relates to air vent valves intended to relieve vacuum developed in conduits, while also serving as check valves preventing elevated pressures from propelling fluids past the valve. A principal application of the invention is for vacuum relief of domestic sewage piping systems in residential, commercial, industrial, and institutional buildings. Of course, any conduit system requiring the above aspiration scheme may utilize the invention.
2. Description of the Prior Art
Domestic sewage-piping systems usually have one or more conduits open to the atmosphere, for relieving vacuum conditions which would otherwise disrupt effective evacuation of wastewater. In most buildings, one or more such conduits extend through the roof and open above the building.
At different times, both vacuum and elevated pressures can exist within a sewage system. Vacuum, or pressures below ambient pressures, can prevent wastewater from being evacuated. High pressures, which could arise from decomposing organic materials, would not ordinarily interfere with evacuation of wastewater from the building, but can enable objectionable, malodorous gasses to enter occupied spaces if not conducted away therefrom. The open vent pipe ordinarily employed both relieves vacuum and also vents objectionable gasses from the building.
It would be possible to connect a unidirectional check valve to a domestic plumbing wastewater system in place of the permanently open conduit conventionally employed. Any valve which admits ambient air into the plumbing system while preventing noxious or objectionable vapors from entering occupied spaces would achieve the desired flow scheme, but is potentially subject to problems which can plague non-spherical valves. One problem is that non-spherical valves may be broad surfaces which can accumulate moisture and other substances which can cause the valve to stick to its seat. Light conditions of vacuum might then be unable to open the valve. Another problem is that if a non-spherical valve misaligns with its seat, it may potentially fail to seat properly. This could allow objectionable gasses to pass to occupied spaces.
The prior art has proposed valves for relieving vacuum while preventing discharge of gasses in the opposite direction. U.S. Pat. No. 3,863,671, issued to Bernard Heimann on Feb. 4, 1975, shows a valve for controlling vacuum wherein a counterweight and lever are connected to the valve. The present invention operates independently of and lacks any counterweight and lever.
U.S. Pat. No. 4,142,645, issued to Donald G. Walton on Mar. 6, 1979, describes a ball valve utilized for maintaining vacuum conditions in home canning operations. The ball vents ambient gasses from a receptacle responsive to connection to a source of suction. By contrast, the present invention is a self-contained assembly wherein the conduit to which it is connected provides both vacuum and also elevated pressures. The novel valve relieves vacuum prevailing in the conduit to which it is connected, while preventing elevated pressures therein from discharging fluids past the valve. The valve of Walton cannot relieve vacuum developed within the container associated with his valve.
U.S. Pat. No. 4,250,360, issued to Gustav E. Svensson on Feb. 10, 1981, shows a valve operated by tilting or acceleration of the valve housing. Tilting and acceleration cause the valve to overcome resistance of a spring biasing the valve in the closed position. By contrast, the present invention does not rely upon tilting or acceleration of the housing, and does not require a spring.
U.S. Pat. No. 4,806,082, issued to Jacob W. Schenk on Feb. 21, 1989, sets forth a valve assembly incorporating two valves each acted upon by its own spring. The present invention requires but one valve and requires no springs.
U.S. Pat. No. 4,991,623, issued to Kurt S. B. Ericson on Feb. 12, 1991, shows an automatic valve assembly wherein the valve is a disc. By contrast, the valve of the present invention is a rigid sphere or ball.
U.S. Pat. No. 5,033,504, issued to Dieter H. F. Kallenbach on Jul. 23, 1991, shows a relief valve which utilizes a flexible diaphragm. The present invention utilizes a ball as the valve, and does not have a flexible diaphragm.
U.S. Pat. No. 5,105,848, issued to Dieter H. F. Kallenbach on Apr. 21, 1992, sets forth an automatic relief valve which also utilizes a flexible diaphragm absent in the present invention. The present invention has a spherical valve which overcomes problems of non-spherical designs.
U.S. Pat. No. 5,419,366, issued to Ian F. Johnston on May 30, 1995, shows a valve assembly wherein the valve is an elastomeric diaphragm. By contrast, the valve of the present invention is spherical, which design avoids problems associated with non-spherical designs.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.